Power conditioners use an output from an adjuster as an input and an input value as a target output value to provide an AC power supply (hereinafter referred to as an “output”) to a load with a voltage value, a current value, or a power value that is proportional to the target output value. Some power conditioners are based on a phase control scheme (see FIG. 15(a)), and others are based on a scheme for controllably turning on or off the output to control the ratio of an “ON time” to an “ON time+OFF time” (the ratio is hereinafter referred to as a “load factor”) so that the ratio is proportional to the target output value (see FIGS. 15(a) and 15(b)) (for these control schemes, see, for example, Patent Literature 1 or 2).
Furthermore, two schemes are available for making the load factor proportional to the target output value. One of the schemes sets the “ON time+OFF time” for the output to a constant time and makes the corresponding ratio of the “ON time” to the “ON time+OFF time” proportional to the target output value (see FIG. 15(b); this scheme is hereinafter referred to as a “time proportioning scheme”). The other controllably turns on or off the output every minimum time for which the output to the load (AC power supply) is on or off (the minimum time is hereinafter referred to as a “unit time”), and makes a load factor for a sufficiently long time proportional to the target output value (see FIG. 15(c); this scheme is hereinafter referred to as a “time-sharing output control scheme”). The unit time according to the time-sharing output control scheme is an integral multiple of a half cycle, and is normally a half cycle or one cycle.
The time-sharing output control scheme includes an integrator that integrates the target output value (0 to 1 or 0 to 100%) every unit time cycle. The time-sharing control scheme makes the load factor proportional to the target output value by repeating the following processing every unit time. When the value of the integrator is greater than any threshold value (fixed value), the output is kept on during the unit time. At the same time, 1 (100%) is subtracted from the integrator that integrates the target output value.